Lubricant



Patented Jan. 1, 1941 UNITED STATE LUBRICANT Bert 11. Lincoln, Ponca City, Okla... and Gordon D.

Byrkit, Niagara Falls, N. Y., assignors to Continental Oil Company, Ponca City, Okla a corporation of Delaware No Drawing. Application November 8erialNo.4

. j ..c1.1m.. (crass-49.1)

This invention relates to addition agents and lubricating compositions containing the same and is a continuation-in-part of our'copending application, Serial No. 330,950, filed April 22, 1940.

, Present-day mechanical devices require lubri-. eating oils of high film strength and of high oiliness characteristics. It-has been found that the present-day hydrocarbon lubricants of the very highest quality are deficient in these two very important characteristics. These two properties are of vital importance under conditions of thin film lubrication where the lubricant has been squeezed from between thefri'ction surfaces due to high pressures, slow speeds, and other causes. It is readily seen that the viscosity or the body of the lubricant plays no part in this. yp of lubrication and that the remaining film of oil should tend to keep the coefilcient of friction as low as possible and must have a very high film strength and be of high oiliness value to prevent rupture of the filmof the lubricant, which would cause seizure.

Mechanical devices are being designed for higher pressure operation, and the film strength of the best quality straight hydrocarbon lubri- 1 cents has been found to be too low and not sumcient; therefore an invention which provides the means of improving the film strength of these lubricants is of great importance to the art of lubricant manufacture and'to the designer and fabricator of mechanical devices.

Substantially, all machines operate in part or at times totally under conditions of boundary or thin film lubrication, under which conditions the oiliness or unctuosity of the lubricant is the first and primary requisite of eflicient operation. Those skilled in the. art of lubricant manufacture or machine manufacture will readily appreis lubricated-"from a sump by pumping-or circulating the, lubricant, there is always a short period of time during which the rubbing surfaces must operate'under conditionsof dry'friction if *trating or adsorbing on the metal, andleaving a film of lubricant with high oiliness character which remains on the metal surface irrespective- 01' the length of time the machine is idle.

This high oiliness film is very even and results in smooth operation whichmay be easily dis-- cemed by the experienced operator and lubricating engineer.

When the hydrocarbon lubricants are diluted with unburned fuel or with other light hydrocarbonsj, the'small degree of oiliness of the original hydrocarbon lubricant is greatly decreased. We

have found that the addition of the product of our invention to hydrocarbon lubricants more than compensates for the loss in oiliness and loadcarrying ability by dilution.

' One object of our invention is to provide a lubricating composition having improved film ity of layers or films on the surface 01 the metal,

which films are very tenacious (they have a high film strengthTa'nd have the property of reducingthe coefiicient of friction to a greater extent than any known lubricant. The compounds which most readily are adsorbed by metals are ones consisting of polar molecules, that is, molecules of unsymmetrical electrical character which contain an atom or group of atoms eihibiting a secondary or residual valence. Thesepolar compounds tend to produce regimentation of the molecules of hydrocarbon oil when added thereto. If a metal is immersed in a stronglypolar compound, a

- regimentation or cybotaxis oi. the molecules will take place in the adsorbed film, the molecules being oriented with'respect to the surface of, the

metal bywhichthey are adsorbed. The films of polar compounds, adsorbed by a metal, can be" plainly seen and the orientationof the polar molecules on the metal surface ascertained by X-ray.difiiraction methods, :in which a monochromatic JX=ray beam is passed through the ad- I sorbed' film's at an angle. The series of films acts as a diffraction grating, and a diiifractcdv beam will be reflected from the planes of the :films and can be recorded photographically. The

' ordinary hydrocarbon lubricants are used- With dry friction, "the wear onfriction surfaces is exf treme; and during cold weather when the lubri cant is sluggish or during periodswhen thelubrieating system is'not-functioning properly for one reason or another, rubbing surfaces may not only 'suiler considerable, wear but may be damagedto the point where they must'be replaced. The product 01'. our invention has the very important prop-'- erty oi reacting with; the metal surfaces, pene X-ray photographs will clearly show the orientation of the molecules by cl .aracteristic pictures.

X-ray investigation has shown that strongly lubricatingcompositions of halogen bearing orload and the like.

3 gano-boron esters of the type which contain the B-OR group (in which R is an organic radicle) and improved lubricating compositionscontaining minor amounts of such addition agents.

The use of organo-boron compounds broadly in lubricating compositions is not new. Their principal use in lubricating compositions is disclosed in Patent No. 2,234,581, wherein acidic organo-boron compounds are disclosed for the purpose of preventing oxidation of lubricants, especially when the same are subjected to high temperatures and gases which tend to promote oxidation. That patent, as indicated, relates to the use'of acidic materials, and the amounts specified for use are in all cases minute. While organicsubstituted boric acids, that is, compounds having the B-OH group, are disclosed therein, these are described as being of low solubility and less desirable,

In addition to the disadvantage of low oilsolubility, the acidic organo-boron compounds are corrosive to sensitive bearing metals, such as are commonly used in modern internal combustion engines.

We have found, however, that a much more satisfactory sub-generic class of organo-boron compounds .for the foregoing uses are those of the ester type and which are additionally characterized by the presence of combined halogen in the molecule.

The ester type material is preferable for use I in that it does not have the objectionable high reactivity above pointed out which is possessed by the acidic material. In the same concentrations as suggested by the prior art for the acidic type material, our ester type material is quite efiective from the standpoint of inhibiting oxidation without, however, possessing the undesirable properties of the acidic material. The additional char- 'acteristic of our improved addition agent, namely, that it contains halogen, gives rise to further advantages, the most important of which may the compounds makes it possible to achieve effects on the metal surfaces, such as the bearings, which are not only impossible by the prior art uses of the acidic materials, but which the prior art deliberately sought to avoid by keeping down to as low as possible the concentrations within which such acidic materials were employed.

The addition agents of our invention are desirably strongly polar 'for the reason that one of the principal purposes for which they are present in the lubricating compositions of our invention is dependent upon their ability to react in a chemical or physico-chemical fashion with the bearing surfaces being lubricated. This chemical or physico-chemical action by which the addition agents of our invention improves the lubricating compositions containing the same is two-fold, and the efiects thereof are likewise two-fold.

In the first place, the strongly polar nature of the addition agents causes the same to be oriented as an adsorbed film on the bearing surfaces sought tobe lubricated with the attended advantages, such as higher oiliness; less tendlhis strongly polar nature of A second and equally important effect of the increased polarity of our improved addition agents is the increased film strength of the lubricant containing the same, attributable to the function of the cooperative eifect of the halogen and the R BOR"group present in the molecule as a filmstrength improver.

The presence of halogen in the molecule has an additional advantage in that it renders the compound much less volatile so that it will not be so readily evaporated from the lubricating compositions during use at high temperatures. At this point it may be well to note that for most purposes the addition agents should have a vapor pressure less than atmospheric at a temperatur of C. and preferably at'l70 C.

Whenoneof the desired effects of the presence of the addition agent is an increase in the film strength of the lubricant, the ester materials of this invention are particularly advantageous be-.-

cause their higher solubility, as compared with the acidic materials of the prior art, makes it possibleto incorporate amounts which are much more -efi'ective for that purpose; that is, in amounts higher than .75% or preferably above The upper limit of the concentration of addition agents is determined by factors such as the limit of their solubility; reasons of economy,

-etc. Our invention, therefore, contemplates that these addition agents may be used in lubricating compositions such as those which comprise a mineral oil base in effective amounts up to the limits of their solubility in the oil, there being generally no reason, however, for including more than about 20%.

The broad class of-organo-boron esters contemplated for use by this invention contains two important sub-divisions respectively represented by the following formulas:

a O-R' B I x in which R and R are organic radicles and X is a radicle of the class consisting of R" and --OR"' where R" and R are organic radicles; and

' R4=B-0R in which R is a divalent organic radicle, and R is an organic radicle.

Other sub-divisions of the broad class of esters contemplated hereby are the following;

RzBOR, in which R and R are organic radicles, at least one or which contains four or more contain at least one carbon-boron bond, and at least one organic radicle is removable by saponification. R and R are usually hydrocarbon radicles but are not necessarily hydrocarbon radicles, and they may contain besides carbon and hydrogen also other elements including oxygen, sulphur, halogen, phosphorus, or metals. Other examples of our compounds are chlorophenylboric B. Oxygen-containing organic radicles--Continued-.

2. Of the ketone type-Continued. Adipyl- Benzoylene Butyry Isobutyryl Carbothoxy Cresotyl Desyl Glutaryl Glycolyl Melonyl Oxalyl Phthalyl Succinyl 3. f the ester type, i. e. 1

Derived from hydroxy-esters b the removal of the hydroxyl group, as for examp e, by the removal of thehydroxyl group from the following esters? a. Esters of ydroxy acids, a. a.

Esters formed by substitution or any oi the R grougs listed above for one or more of thedacid ydrogen atoms of the following Lactic acid Hydracrylic acid Citric acid Tartaric acid Ricinoleic acid Hydroxy-stearic acid Hydroxy-chlorstearic acid Cyclohcxanol carboxylic acids Hydroxybcnzoic acids Salicylic acid Hydroxy-phthalic acids Hydroxy phenyl-bcnzoic acids Naphthol carboxylic acids I Esters of polyhydroxy alcohols and phenols in which at least .one hydroxyl group remains unsubstituted, for example-esters iormed by esteriiyirg the iollowirg so that at least one hydroxyl group remains in the resulting ester:

Ethylere glycol .Diethylene glycol Propylere gylcols Butyler'a glycols Poly-hydroxy benzenes Dihydruxy-benzenes Resorclrol Catechol Hgdroqulrone Triydroxybenzenes Pyiogallol 4. Hydroxy radicles Hydroxy-ethyl Hydroxy-butyl Hydroxy-amyl Hydroxy-ghenyl Hydroxyenzyl Hydroxy-cyclohexyl Amy] hydroxy-phenyl Laur lhydroxyhenyl Cety hydroxy-p enyl Di-amyl hydroxy-phenyl Lauryl hydroxy-ben zyl Amyl hydroxy-cyclohexyl Phenyl hydroxy-phenyl Phenyl hydroxy-benzyl Hydroxyphenylhenyl Hydroxy henylenzyl Hydroxy nzyl-phenyl Hydroxybenzoyl-phenyl Hydroxy-benzoyl Hydroxy-stearoyl Salicylal C. Sulphur-containing organic radicals.

Exam les are any of the radicles listed under B in which a Sltllp ur atom has been substituted for one or more oxygen a oms, e. g.,

s ll R-C- s where R is an aliphatic radicle (e. g., methyl, ethyl, butyl, lauryl), a cyclo-aliphatic radicle (e. g., cyclohexyl, methylcyclohexyl) or an aromatic radicle (e. g., phenyl, benzyl, tolyl, xenyl, naphthyl), and R is a divalent organic rad1c1e, e. g., methylene, ethylene, amylene, phenylene, Ce |-CH:, e 4-CeH4 Thio-benzoyl-benzyl Thio-stearoyl-benzyl Thin-stearoyl-phenyl 'lhlc-acetyl-phenyl C. Sulphur-containing organic radicalPContinued.

Specific examples-Continued.

Thio-acetyl-benzyl Mercapto-ggenyl Mercaptonzl Mcrcapto-ethy Mercapto-butyl Mercapto-benzoyl Mercapto-stcaroyl Mercapto-thio-benzoyl Mercapto-thic-atearoyl I Mcrcapto-thio-stearoyl-phenyl Mercafito-thio-benzoyl-phenyl Laury mercaptohenyl Lauryl mercaptoenzyl Thlenyl Thiazyl It is to be understood thatthe foregoing organic radicles may have one or more atoms of halcgen, and more specifically of chlorine, substituted for one or more hydrogen atoms in the preparation of the halogen bearing esters which comprise the addition agents of this invention.

Esters of the type RRBOR' or-RzBOR may be made by replacing one ester group of a triester by reacting the ester with only enough Grignard reagent of the formula RMgBr to carry the reaction just one step. The second step may then be carried out with the same Grignard reagent, or a difierent one, R'MgBr, depending on whether R and R. are to be the same or difierent.

The esters of type RB(OR')2 may be prepared as follows:

/OR' 3ROH BC]; B0R' (the triester) The triester is reacted with RMgBr R on R and R may be any organic radicles, for example ethyl and CH2CH2CH2CH2C1 respectively.

The above type reaction makes use of the Grignard reagent and reaction. The above reaction would give a product in which the R's are the same.

It is possible to use phenyl, chlorphenyl, naphyl, aliphatic, aliphatic substituted aromatic, and aromatic substituted aliphatic radicles to form the triester. It is preferable to have the chlorine in the radicles prior to the reaction.

By varying the alcohol and the Grignard reagent it would be possible to obtain a great variety of esters.

An aromatic radicle may be placed in the ester linkage in the following way:

H Na-O 01 BC]: 3 B 0 C] reagent to obtain the ester containing a carbon to boron-linkage. I

Specific examples of the organo-boron esters of this invention are:

ooinnoi claws OCcHuCl .ooinnciz where M is a divalent metal, e, g., the alkalineearth metals; I a 7 It is sometimes advantageous to combinemore than one'ot these compounds in a blend to ob-;

tain particular properties. 'We accomplish this by mixing two or more of these compounds to-"' gether' and blending the mixture with hydrocar-. bon oil, or by blending one in the hydrocarbon oil, blending the second into this mixture, and so on until th composition is complete.

We have found that the organic boron c0m-' pounds above se't'forth may be more effective in .some compositions if. a comparatively small amount of halogengfree, oxy en-containing can bon'"conmo'und is included invthe composition. j 1 The oxygen-containing carbon compound may be of aliphatic, aromatic, or hetero-cyclic nature and may be blended withthe organic boron compound in amounts ranging from 5 to 50 percent.

It will be understood that certain features sub-combinations are or utility and may be employed withoutreference .toother features and sub-combinations; ,Thisis contemplated by andis within the scopevof-ourclaims. It isfurther 1 obvious that variouschanges may be made in dei Wethereforeparticularly Y78 3. comprising incombination ,a 7

" tinctly as our invention:

tails within the scopefof ourfclaims without; de-

parting from the spirit of our'invention." Itis, ,irxtherefore, to be understood that our invention is not to be limited to the specific details shown and described.

Other modes oi" applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or theequivalent or such be employed;

point out and disa *P 'flpdi ion-iofa hydrocarbon oil and from 001% {20% of an oil s'oluble halogenbearing organo-boron ester containing at least .one carboneboron bond and having the formula:

here R", and R1" organic radiclles.

{A lubricantgcomprising in} combination a. niai; l'flwlflq fbtahydrocarbon'oil and'rm 001 to?about 20%1oi anxo il-soluble halogen- I ter containingat least one carbon- -boron li'ibricant*'coniprisins,,1n combination a major proportion of a hydrocarbon oil and from" in which Ft is a divalent organic radicle and R is an organic radicle.

4. A lubricant comprising in combination a major proportion of a hydrocarbon oil and from .001% to about 20% of a halogen-bearing organoboron ester containing at least one carbon-boron bond and having the formula RnB(OR')3-n in which R and R represent organic radicles and n is an integer less than 3.

5. A lubricant comprising in combination a major proportion of a hydrocarbon oil and from .001% to about 20% of a halogen-bearing organoboron ester containing at least one carbon-boron bond and having the formula-RB(OR')-z in which R and R are organic radicles.

6. A lubricant comprising in combination a major proportion of a hydrocarbon oil and from 12 .001% to about 20% of a halogen-bearing organoboron ester containing at least one carbon-boron bond andrhavin g the formula RzB.OR' in which R and R are organic radicles.

7. A lubricant comprising in combination a major proportion of a-hydrocarbon oil and a BERT H. LINCOLN. GORDON D. BYRKIT. 

